Answer:
-1/2
Step-by-step explanation:
- arrange the equation in the y=mx+b form
2x + 4y =21, subtract 2x from both sides of the equation
4y= -2x +21 , divide both sides by 4
y= -1/2x +21/4
-compare the slopes m of the 2 equations
y= kx -12, has the slope k
y= -1/2x +21/4, has the slope -1/2
- If the lines are parallel then they have the same slope
Therefore, k= -1/2
